dtmthinner.h

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#ifndef OPENSWMMVIS_MESH_DTMTHINNER_H
#define OPENSWMMVIS_MESH_DTMTHINNER_H
 
#include "map/mapextent.h"
 
#include <QPointF>
#include <QString>
#include <QVector>
 
#include <functional>
 
class GDALDataset;
 
namespace mesh {
 
using DTMProgressFn = std::function<bool(double)>;
 
struct DTMThinnerLimits
{
    qint64 maxGridBytes      = qint64(2048) * 1024 * 1024; 
    qint64 maxRetainedPoints = 64ll * 1024 * 1024;         
};
 
struct DTMThinnerOptions
{
    double gridSpacing        = 0.0;   
    double normalDotThreshold = 0.95;  
    bool   useAverageDot      = false; 
    int    maxPoints          = 0;     
    int    maxIterations      = 0;     
 
    // ── Poisson-disk minimum spacing (post-thinning reduction only) ──────────
    // NOTE: these two fields are NOT consumed by DTMThinner.  They are read by
    // the mesh-generation pipeline, which applies the Poisson-disk filter in
    // the MESH CRS after generatePoints()/readPixels() has returned and the
    // candidates have been reprojected.  Only ever removes surviving points.
    bool   useMinSpacing  = false; 
    double minSpacing     = 0.0;   
};
 
class DTMThinner
{
public:
    DTMThinner();
    ~DTMThinner();
 
    DTMThinner(const DTMThinner &) = delete;
    DTMThinner &operator=(const DTMThinner &) = delete;
 
    bool open(const QString &filePath, int band = 1);
    void close();
    [[nodiscard]] bool isOpen() const noexcept;
 
    [[nodiscard]] QVector<QPointF> generatePoints(const MapExtent        &domain,
                                                   const DTMThinnerOptions &opts = {},
                                                   QVector<double>        *outZ  = nullptr,
                                                   const DTMProgressFn    &progress = {},
                                                   const DTMThinnerLimits &limits = {}) const;
 
    [[nodiscard]] double  pixelSize() const;
    [[nodiscard]] QString crsWkt()    const;
    [[nodiscard]] QString errorMsg()  const { return m_errorMsg; }
 
    [[nodiscard]] double sampleAt(double x, double y) const;
 
    static constexpr qint64 kMaxReadBufBytesDefault = qint64(256) * 1024 * 1024;
 
    // NOTE: these three constants shape multi-band thinning geometry and thus
    // its OUTPUT for configurations that engage banding.  Changing any of them
    // requires bumping MeshStageCache::kFormatVersion (meshstagecache.h) so
    // stale terrain-cache entries cannot be served.
    static constexpr qint64 kMaxGridBytesDefault      = qint64(2048) * 1024 * 1024;
    static constexpr qint64 kMaxRetainedPointsDefault = 64ll * 1024 * 1024;
    static constexpr int    kMaxThinningHalo          = 64;
 
    void sampleMany(const QVector<QPointF> &xy,
                    QVector<double>        *outZ,
                    qint64                  maxBufBytes = kMaxReadBufBytesDefault) const;
 
    void readPixels(const MapExtent  &bbox,
                    QVector<QPointF> &xyOut,
                    QVector<double>  &zOut) const;
 
private:
 
    bool fillBandGrid(double x0, double y0, double step, int cols, qint64 rows64,
                      qint64 rBegG, qint64 rEndG,
                      QVector<float> &gx, QVector<float> &gy, QVector<float> &gz,
                      QVector<quint8> &active, qint64 *nActiveOut,
                      const std::function<bool(double)> &tick) const;
 
    GDALDataset *m_ds        = nullptr;
    int          m_band      = 1;
    double       m_geo[6]    = {};
    double       m_invGeo[6] = {};
    int          m_w         = 0;
    int          m_h         = 0;
    double       m_noData    = 0.0;
    bool         m_hasNoData = false;
    mutable QString m_errorMsg;
};
 
} // namespace mesh
 
#endif // OPENSWMMVIS_MESH_DTMTHINNER_H